Safety appliance for hydraulic brake systems



Aug. 11, M42. J. B. BOURGEOIS' 2,292,92

SAFETY APPLIANCE FOR HYDRAULIC BRAKE SYSTEMS Filed June 24, 1940 iffidezr' (74/70 3.30 e f 16 Mill/11004 A y 0 Patented Aug. 11, 1942SAFETY APPLIAN CE FOR HYDRAULIC BRAKE srs'mms John B. Bourgeois,Worcester, Mass. Application June 24, 1940, Serial No. 342,122

8 Claims.

This invention relates to an appliance for hydraulic brake systems andmore particularly to a device which I term a sub-master cylinder forapplication to the conventional hydraulic brakes for vehicles.

Objects of the invention include the provision terminates in an opening26 behind a wide splash guard 28 to prevent escape of the oil. This capis screw-threaded into the top of the reservoir 1 l8; and can be removedso as to enable replenof a safety means in a hydraulic brake system toprevent the escape of the liquid from the master cylinder in case ofbreakage of a line to a wheel; the provision of a sub-master cylinderfor the purpose described which will not interfere with the normaloperation of the brakes, but which will prevent loss of liquid from themaster cylinder as to one pair of brakes when a line in the other pairleaks or breaks; and the provision of a sub-master cylinder for thepurpose described which is simple in construction, positive inoperation, and relatively inexpensive to manuiacture.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawing, in which Fig. 1 is asectional view thru a sub-master cylinder which embodies one form of myinvention, and shows its attachment to the master cylinder;

Fig; 2 is a section on line 2-2 of Fig. 1;

Fig. 3 is an elevation of the reservoir cap;

Fig. 4 is a detail of the piston; I Fig. 5 is an elevation of the valvecap;

Fig. 6 is a section on line 6-6 of Fig. 1;

Fig. '7 is a section of a valve;

Fig. Bis an elevation of the valve looking in the direction of arrow 8in Fig. '7; and

Fig. 9 is a section of a sub-master cylinder embodying a modified formof the invention.

It'is well known that when a hydraulic brake line breaks or even leaks,the liquid escapes from the entire system and especially from the mastercylinder, so that the brakes become inefiective and hence dangerous. Thepresent invention provides a positive means to overcome this disabilityand to reduce the hazard of brake failure. v

Referring to Fig. 1, there is generally shown a master cylinder II) fora vehicle hydraulic brake system. My novel appliance, indicatedgenerally at H, may be attached to the cylinder I 0 bya short hose l4,or may be directly attached, thus dispensing with the hose. Theappliance comprises a casting embodying mainly a cylinder I6 and oilreservoir l8, the latter having a cap -l'll which is formed with an airvent 22,- which is ishment of the oil.

A valve is provided to enable replenishment of oil to the hose l4 and.master cylinder III, while preventing the formation of air pockets.

Apiston 32 is located in cylinder l6, and oppositely extending rubbercups 34, 36 are provided at each end of the piston to act as washers,thus preventing seepage of oil in either direction past the piston. Alight spring 38 abuts cup 34 to position the same tightly against the 42and cup piston at all times. A small metal cup 40 fits inside rubber cup36 and acts as an abutment for relatively heavy spring 42, to preventthe rubber from being cut by the spring. This spring 40 togetherposition rubber cup 36 and prevent its displacement relative to thepiston at. all times. Also, of course, spring 42 exerts pressure on thepiston to normally retain it at the left end of the cylinder, as seen inFig. 4. There is a vent 44 and the portion of cylinder l6 to the rightof the piston, this vent assuring a full load of oil in this side of thecylinder.

At the end of cylinder l6 opposite to the master cylinder connection,there is an enlarged portion 46 which has an internal screw-threadedbore alined with and communicating with the cylinder walls. A nut 50 isadapted to be threaded into the bore, and this nut is hollow as at 52 toreceive a valve 54. This valve is shown in detail in Figs. 7 and 8, andcomprises a cup having an end flange 56 which receives the force ofspring 42 and is thus resiliently pressed against a washer on the insideof the bore in nut 50 as shown in Fig. 1. Apertures 58 are providedinthe sides of the valve and a rubber cup 60 is secured to the bottom ofthe valve at 62, but having its walls free to normally cover theapertures. Pressure from the left of the valve in Fig.

led as shown; down to a narrow neck '24 and '7 will cause the oil toenter the apertures 58 and displace the walls of the rubber cup in thedirection indicated by the arrows in this fig ure. Release of thepressure will allow the walls of the rubber cup to retlllnto normalposition closing apertures 58, to thus act as a check valve. Nut 58 isattached to a line 64, preferably leading to both front wheel brakes orboth rear wheel brakes.

A lock is provided in the cylinder I6 to prevent escape of the piston32, and thus prevent escape of liquid from master cylinder I 0, in theevent between the'reservoir l8 that nut 50 should be lost. This lockcomprises a generally circular spring band 66 which is resiliently heldin a circumferential groove in the cylinder wall, and this spring has abent out portion 63 for the reception of a laterally extending lockinglug ID on a washer (I2, to position the spring and to prevent collapseof the latter due to radial pressure. A backing up spring I4 is arrangedto hold the washer in place.

The modification of Fig. 9 is generally similar to Fig. l, but thepiston 32 has a thru bolt 16 which is used to secure the cups 34, 36thereto, thus avoiding use of spring 38 and cup 40. The valve 54 islocated permanently in the nut 50 by means of an end flange 18, againstwhich abuts a spring 80, the latter holding valve 54 against the nut 50in the manner of spring 42. A lock, comprising a spring band 84, bar 86with extending lugs 88, and spring 30, assembled as shown in Fig. 9,perform the function of lock 68, 12, but in this case, the spring 92,which bears thereagainst, its also retained even in the absence of nut50 and its valve.

The operation of the device is as follows: with the parts as shown inFig. l, the hoses I4, 64 and the cylinder being filled with brakeliquid, the brake pedal is actuated to stop the vehicle, and thepressure from the master cylinder is transmitted to piston 32, whichthereupon moves against tension of spring 42, exerting pressure on theliquid in the cylinder. Vent 44 is closed by a very small travel of thepiston, as will be clear. The now built-up pressure in the cylinderforces the rubber cup 60 to yield, and the liquid flows thru apertures58 to exert pressure on the liquid in hose 64, thus actuating the brakecylinders, not shown. Upon release of the brake pedal, the brakecylinder springs will force the fluid in hose G4 backwards, and spring42 will thus yield sufficiently to let valve 54 raise oi the nut 50 tolet the liquid escape from the hose into the cylinder. It will be seenthat valve 54 is thus a sort of double check valve. It is to be notedthat the master cylinder spring, not shown, must be balanced withspring42, so as not to render it too hard to actuate the brake pedal.When the pressure in the master cylinder is released, spring 42 willpush piston 32 back'to normal position.

In case of failure of the line 64, so that the fluid escapes therefrom,the piston 32 and rubber cups 34, 36 prevent escape of the fluid fromthe master cylinder. The flange of cup 40 will act as a stop againstspring 68 and prevent the piston from traveling far enough to the rightin Fig. 1 to uncover vent 44, and also the cup 40 will prevent anypossible tendency of the rubber cup 36 to turn inside out, underpressure from the master cylinder, against the spring 66.

The form of the invention shown in Fig. 9, works similarly to that 'ofFig. 1, but in this case, spring 32 acts only to resist the piston,while spring 80 is now, of course, the check valve spring.

It will be seen from the above that if this appliance be interposed in aline to the front brakes for instance, and hose 64 breaks or leaks, thattheliquid cannot escape from the master cylinder, but only from the line64 to the front wheels, hence the rear wheels will still be operative.Naturally it is intended to apply the invention to both front and rearwheels, and it is contemplated that one of my sub-master cylinders couldbe applied to the line for each wheel, so that only one brake at a timecould become inoperative.

mally closing said apertures.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. In a safety appliance for a hydraulic brake system, a cylinder, meansat one end thereof for connection to a fluid pressure device, means atthe other end of said cylinder for connection to a conduit, a piston insaid cylinder, means urging said piston towards said first mentionedmeans, a valve in said cylinder on the side of the piston towards saidsecond mentioned means, said'second mentioned means comprising a nuthaving a bore and a shoulder, said valve seating on said shoulder andsaid bore accommodating said conduit.

2. In a safety appliance for a hydraulic brake system, a cylinder,conduit connecting means at each end of said cylinder, a piston in saidcylinder having means at each end thereof to prevent the escape of afluid past said piston, a relatively heavy spring urging said pistontowards one end of said cylinder, valve means at the other end thereof,means in said valve to allow the escape of fluid therepast and out ofsaid cylinder 'upon movement of said piston against said urging means,and a relatively light spring between said one cylinder end and saidpiston.

3. In a safety appliance for a hydraulic brake system, a cylinder,conduit connecting means at each end of said cylinder, a piston in saidcylinder having means to prevent the escape of a fluid past said piston,means resiliently urging said piston towards one end of said cylinder, arelatively flxed abutment for said piston urgingmeans, valve means atthe other end thereof, means in said valve to allow the escape of fluidtherepast and out of said cylinder upon movement of said piston againstsaid urging means, and separate means resiliently urging said valve in adirection opposite to said piston. Y

4. In a safety appliance for a hydraulic brake system, a cylinder, hoseconnections at each end thereof, a piston in said cylinder, meansassociated with said piston to prevent the escape of fluid therepast, aspring in said cylinder, a check valve, said spring urging said pistonand valve towards opposite hose connections, a reservoir having an inletbetween the piston and valve, said valve being constructed and arrangedto allow passage of fluid under pressure in either direction, aseparable abutment against which said spring urges said valve, and alock in said cylinder to prevent escape of said piston upon removal ofsaid abutment.

5. In a safety appliance for a hydraulic brake system, a cylinder,connections at each end thereof, a piston in said cylinder, a flxed lockin said cylinder, a spring reacting against said lock and said piston tourge the latter'towards one connection, a cup-shaped element having alip flange bearing against the end of the cylinder at the otherconnection, a separate spring engaging said flange and an abutment,there being apertures in said element and resilient means nor- 6. In asafety appliance for a hydraulic brake system, a cylinder, connectionsat each end thereof, a hollow nut threaded into one connection, acup-shaped element having a flange to bear against said nut, a pistonhaving rubber washers at each end thereof in said cylinder, a relativelyheavy spring bearing against said flange and one of said washers to urgesaid piston away from said element, a light spring at the other side ofsaid piston and bearing on the other of said a vent extending thru saidbody to both sides of washers, apertures in said element, means to theflange,1a splash guard in the formof a flange normally 'olose saidapertures, and a circular at one side of said first named flange, saidvent spring in said cylinder having a part extending having an orificebetween said flanges. 2

into the path of said piston to retain the same in 8. A closure cap asrecited in claim 7 in which the cylinder upon removal of said nut. I 5the flanges are generally parallel and the guard '7. A closure cap for aliquid holding reservoir flange is adaptedto extend into the reservoir.

comprisingasubstantiallysolidbodyhavinga 7 flange adapted toseat onthereservoir opening, JOHN B. BOURGEOIB.

